This chart shows the contribution to the "greenhouse" effect. The gray shows what is natural, and the green shows what is manmade. Our contribution is so small as to be statistically insignifigant.
These numbers mean something 9sublime. They tell a truth that goes beyond what you see and what you believe humanity's place and effect in the world is. A medium sized volcano can produce more CO2 in an 8 hour period than all of humanity can produce in a year. A truely large volcano like Krakatoa put more CO2 out during its eruption than mankind has produced since we walked out of the jungle. Face it. With regard to global climate, we are insiginifigant. We can certainly dirty up the place, no doubt about that, but dirtying up our living area is a far cry and a long shot from having an effect on the global climate.
Folks like PLC1 are great at parrotting the information that environmentalist organizations put out for public consumption, but it is clear that he has never looked at the information and asked the logical questions. Information is useless unless you are able to put it into some context, ask relavent questions and determine whether you are being told the truth or not.